1. Field of the Invention
The present invention relates generally to a scrambling sequence generation method for use in device-to-device communication and, more particularly, to a method and apparatus for generating a scrambling sequence based on an initial value determined as a function of at least one of a transmission device identifier, a reception device identifier, and a preconfigured value.
2. Description of the Related Art
In typical data communication, a transmission device scrambles a bit block of data to be transmitted with a scrambling sequence, modulates the scrambled bit block to generate a modulated signal, and transmits the modulated signal to a reception device. The reception device demodulates the received signal into the data bit block and descrambles the data bit block with the same scrambling sequence used by the transmission device. The scrambling process is provided to randomize the influence of an interference signal to the data bit block when the transmission device and the reception device share information necessary for generating the same scrambling sequence.
The 3rd Generation Partnership Project (3GPP) is an asynchronous cellular mobile communication standard organization that specifies how to apply scrambling to the data bit block transmitted on downlink and uplink data channels in Long Term Evolution (LTE), as one of the next generation communication systems. According to LTE standard, the scrambling sequence is the Gold sequence with a length of 31, which is generated from two m-sequences having different generation polynomials. The initial value of one of the two m-sequences is defined in the LTE standard, and the initial value of the other one of the two m-sequences is determined according to the purpose of the physical channel to which the scrambling sequence is applied.
Recently, the 3GPP has discussed Device-to-Device (D2D) communication in LTE, in addition to legacy radio communication between a base station and a terminal. When the D2D communication is supported in LTE, it is possible to apply the above-described scrambling to obtain an interference randomization effect in communication between devices.
Since the legacy LTE standard supports only the wireless communication between a base station and a terminal, the scrambling is also designed for such a communication environment. More specifically, in the legacy LTE radio communication environment, since a base station and terminals located within the service area of the base station are the main nodes of data communication, it is easy for the base station and the terminals to share the information required for initializing the scrambling sequence.
When using D2D communication, however, the terminals or devices participating in data communications may be located within the service areas of different base stations, and a terminal or device may fail to receive service from a base station or leave the service area of the base station. In these circumstances, it is difficult to apply the scrambling applied according to the LTE standard, without modification. For example, if the terminals or devices are located in service areas of different base stations, there is an increase of signaling overhead for sharing the information for use in scrambling sequence generation with their serving base stations. Also, when a terminal or device cannot be served by a base station, it is impossible to perform scrambling with the base station-concerned information.
Therefore, there is a need of a method for generating a scrambling sequence suitable for the D2D communication environment distinct from the base station-terminal communication environment.